1. Field of the Invention
The present invention relates to striking tools, such as hammer drills and electric power hammer. More particularly, the present invention relates to a striking tool, such as those described above, which cools the motor incorporated therein by generating an airflow through the motor housing.
2. Description of the Related Art
A typical striking tool includes a main housing which contains a striking mechanism with a tool bit attached to the top end thereof and a motor housing which contains a motor and which is connected to a rear portion of the main housing. When the tool is activated, the motor operates the striking mechanism to cause the tool bit to repeatedly strike a workpiece. As the motor generates heat during operation, a cooling fan is generally provided in such a striking tool. Japan Published Unexamined Utility Model Application No. 57-181586 discloses one such tool, in which a cooling fan is fitted around the motor shaft such that rotation of the motor creates an airflow through the motor housing, thus cooling the motor during operation.
Although a conventional arrangement for cooling the motor such as the foregoing serves its purpose, it is not free from certain defects. For example, the airflow created by the fan in the foregoing disclosure does not reach the main housing, passing through the motor housing only. Therefore, heat generated from the cylinder and other elements of the striking mechanism during operation may significantly raise the temperature of the main housing. At times, the operator may find it uncomfortable to hold the tool due to the heat conducted from the striking mechanism.
As a corrective measure, one or more air inlets may be provided on a side portion of the main housing so as to pass air through the main housing. Problems inherent in this arrangement include the ease with which dust or other foreign matter is drawn into the main housing and the adverse effects such foreign matter has on the operation of the striking mechanism when the tool is used with the attached bit pointed upward. While these problems could be solved if the outlets of cooling air are relocated to a side portion of the main housing, other problems are created. For example, unpleasant air would blow against the operator's hand, thus irritating the operator.